This document discusses fundamentals of polymer engineering, specifically polymer additives and blends. It defines additives as any substance added in small amounts to polymers to improve properties, facilitate processing, or reduce costs. Common additives include stabilizers, lubricants, fillers, plasticizers, and flame retardants. Fillers extend materials at low cost and can improve mechanical properties when well-dispersed. Polymer blends combine two or more polymers and offer benefits like extended temperature ranges, lighter weight, and improved toughness or barrier properties compared to the individual polymers. The classifications, functions, and examples of additives and blends in various polymer applications are covered in detail.

1. Fundamentals of Polymer Engineering
Polymer Additives and Blends
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Course Code: PE-3107
Credits: 3-0-3
Teacher: Engr. Asra Tariq
Email Id: asra.tariq@ntu.edu.pk

2. Additives
 Plastic materials have a wide application range
- Automotive industry
- Electronic sector
- Packaging industry
- Manufacturing of consumer goods
 All these industries are attributed to the incorporation of additives
- Additives are added into
Virgin
Recycled resins
 Polymer industry is impossible without additives
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3. Additives
 Any Substance that is added generally in small concentration to resins in
order to :
 Improve their properties
 Facilitate processing
 Change the physical, chemical or electrical properties of end products.
 Reduce the cost
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4. Requirements of Additives
 Effectiveness in their function
 Stable under processing conditions
 Stable under service conditions
 Economic
 Compatibility with Polymer Matrix
– At molecular level
 Neither Volatile nor extrude to the surface
 Neither bleed nor bloom
 Must have low vapour pressure at high temperature
 Non Hazardous, not impart taste & odour
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5. Classifications of Additives 5
Classifications of Additives
Assist
Processing
Processing
Stabilizer
Lubricants -
External
Lubricants -
Internal
Reduce Cost
Fillers
Diluents &
extenders
Modifying
bulk
mechanical
Properties
Reinforcing
filler
Plasticizer
Toughening
Agents
Surface
Properties
Modifiers
Antistatic
Anti Slip
Anti wear
Adhesion
Promoters
Optical
Properties
Modifiers
Nucleating
Agents
Colorants
Anti-aging
UV
Absorbers
Fungicides
Others
Flame
Retarders
Blowing
Agents

6. Polymer Compounding
 Few polymers are used in pure form since they often
require chemical modification to achieve optimum
properties, and promote non-inherent performance.
 The process of adding essential ingredients to polymers
to achieve these results is termed compounding.
 Compounds must behave as a system, consisting of the
base polymer and additives, selected to achieve a set of
final properties. During compounding, mixing must
occur at two fundamental levels; dispersive mixing and
distributive mixing.
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7. Additives in Polymer Industry
 Additives in plastics provide the means to overcome
- Processing problems
- Property performance limitations
- Restricted environmental stability
 Additives can mean ingredients for plastics but they play a crucial
role in other materials such as
- Coatings
- Lacquers
- Paints
- Printing inks
- Photographic films
- Papers
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8. Additives in Plastics
 Plastic additives are a diverse group of specialty chemicals that are
either incorporated into the plastic
- Before processing
- During processing
- Applied to the surface of the product when the processing is completed.
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9. Additives in Rubbers
 Rubber is a thermosetting polymer which requires curing
(peroxides) in a reaction
The reaction must be controlled by
- Initiators (e.g. sulphur compounds)
- Accelerators (e.g. aniline)
- Retarders, etc.
 The whole compounding and moulding process is to be controlled
by
- Antioxidants
- Antiscorch agents to prevent decomposition
 Plasticizers are added to improve processability
 Adhesion promoters may be added to improve the bonding with
reinforcement
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10. Additives in Rubbers
 To protect cured rubber products during lifetime other additives are
added to provide the resistance from
- Ozone
- Ultraviolet
- Internal heat build-up as the compound is stressed
 Other vital components of a final rubber compound are
- Fillers as reinforcing agents
- Pigments
- Extenders (Low cost fillers)
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11. Fillers
 Fillers are used to extend a material and to reduce its cost
• Few inexpensive fillers are still being used purely for filling purpose
such as
- Walnut shells
- Fly ash
- Wood flour
- Wood cellulose
• Basic low-performance materials such as clays and chalks are still
used very widely
• Modern market demands that fillers should give some additional value
such as improvement in the mechanical properties beside extending
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12. Function of Fillers
• The basic purpose is to fill a compound
- Increase bulk at low cost
- To do this the mix must be homogenous
•Should have good filler-polymer adhesion
The filler also begins to improve the mechanical properties
• Most particulate fillers have a higher specific gravity than polymers
In some cases the addition of fillers can reduce the weight of the compound
- By using the low density filler as compared to polymer
- Adhesion properties are influenced by
• Filler geometry
• Surface texture
- These can be improved by surface treatment
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13. Fillers
Materials/Characteristics
Fillers that have a reinforcing effect are
- Clays
- Calcium carbonates
- Talc
- Silicates
Pigments such as
- titanium dioxide
- Carbon black
Fillers that offer good properties are
- Glass
- Ceramic microspheres
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14. Fillers
For Commercial Polymer
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15. Polymer Blends
 A polymer blend, or polymer mixture, is a member of a class of
materials analogous to metal alloys, in which at least two polymers are
blended together to create a new material with different physical
properties.
 Polymer blends are physical mixtures of two or more polymers
with/without any chemical bonding between them. The objective of
polymer blending is a practical one of achieving commercially viable
products through either unique properties or lower cost than some other
means might provide.
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16. Polymer Blends
 The various economic and property advantages accomplished by blending are
• The opportunity to develop or improve on properties to meet specific customer needs
• The capability to reduce material cost with or without little sacrifice in properties
• Permit the much more rapid development of modified polymeric materials to meet
emerging needs by by-passing the polymerization step
• Extended service temperature range
• Light weight
• The ability to improve the processability of materials which are otherwise limited in
their ability to be transformed into finished products
• Increased toughening
• Enhanced ozone resistance
• Improved modulus and hardness
• Improved barrier property and flame retardant property
• Improved impact and environmental stress cracking resistance, etc.
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17. Polymer Blends
 Types of Polymer Blends
On the basis of miscibility
Basically there are three different types of blends depending on the
miscibility
 Completely miscible blends
 In partially miscible blends
 Fully immiscible blends
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immiscible blends

18. Polymer Blends
 Examples of miscible polymer blends:
 homopolymer–homopolymer:
 polyphenylene oxide (PPO) – polystyrene (PS): The miscibility of the
two polymers in l is caused by the presence of an aromatic ring in
the repeat units of both chains
 polyethylene terephthalate (PET) – polybutylene terephthalate (PBT)
 poly(methyl methacrylate) (PMMA) – polyvinylidene fluoride (PVDF)
 homopolymer–copolymer:
 polypropylene (PP) – EPDM
 polycarbonate (PC) – acrylonitrile butadiene styrene (ABS
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